Atiu Swiftlet vs Great Dusky Swift
Aerodramus sawtelli compared with Cypseloides senex
Side-by-Side Comparison
| Attribute | Atiu Swiftlet | Great Dusky Swift |
|---|---|---|
| Scientific Name | Aerodramus sawtelli | Cypseloides senex |
| Order | Caprimulgiformes | Caprimulgiformes |
| Family | Apodidae | Apodidae |
| Conservation Status | Vulnerable | Least Concern |
| Length | — | — |
| Wingspan | 23.2 cm (9.1 in) | 33.8 cm (13.3 in) |
| Weight | 8.6 g (0.30 oz) | 83.0 g (2.93 oz) |
| Diet | Small aerial insectivore feeding on minute flying insects and spiders; forages over forest canopy and … | Feeds on aerial plankton of tiny insects and spiders; entire diet captured during non-stop aerial … |
| Clutch Size | 2 | 1-2 |
| Population Trend | — | — |
Habitat Comparison
Song & Call Comparison
Atiu Swiftlet
Very high thin twittering; 'tsit' calls over Cook Islands; audible echolocation clicks inside Atiu makatea caves; vulnerable endemic; vocal near cave entrances only
Great Dusky Swift
Loud, churring trill; harsher and louder than other Cypseloides; calls over Iguacu Falls and major Neotropical waterfalls; buzzy 'bzzzt-bzzzt' in aerial groups
Geographic Range & Migration
Atiu Swiftlet
Endemic to Atiu Island in the southern Cook Islands. Resident on this single island; nests in limestone caves. Small and vulnerable population.
Great Dusky Swift
Found in eastern South America from Venezuela and the Guianas south to Bolivia and Paraguay. Resident near rocky cliffs and waterfalls.
Conservation Status
Atiu Swiftlet
Great Dusky Swift
How to Tell Them Apart
Atiu Swiftlet
Tiny; dark grey-brown upperparts; pale grey rump band; underparts whitish-grey; forked tail; Cook Islands endemic restricted to Atiu Island; extremely small range and vulnerable status; plumage similar to Polynesian Swiftlet.
Great Dusky Swift
Very large; entirely dark sooty-brown with pale grey forehead and chin scaling; slightly paler underparts; broad wings; largest Cypseloides swift; South American waterfall specialist with dusky uniform plumage and imposing …
About These Birds
Atiu Swiftlet
A small swiftlet (10 cm) endemic to the island of Atiu in the Cook Islands of the South Pacific. Dark plumage. Aerial insectivore. Nests in small caves and sinkholes (makatea) on the raised coral island. One of the most range-restricted swiftlets, with a tiny population.
Great Dusky Swift
A large swift (18-20 cm) of southeastern Brazil, eastern Paraguay, and northeastern Argentina. Dark sooty-brown plumage. Aerial insectivore, foraging over forested gorges and waterfalls. Nests in large colonies behind waterfalls. The largest member of the genus Cypseloides.